Chromium-Picolinate:  This supplement is a component ( chemical compound) of insulin.  It is sold as a nutritional supplement to treat in a deficit in chromium.  The chromium is needed for the receiving and regulating of glucose in normal, healthy persons.

It is widely used by athletes to regulate blood sugars  by reducing insulin resistance, and cravings for carbohydrates, therefore loosing weight.  I must mention, there is no study to date to back up these claims.

A very small human study ( 15 adults ) was observed for reducing depression, but with further studies they could not reproduce the same effects.  These patients did however, show a reduction in carb cravings and regulating to normal, their appetites.

With all the studies, back and forth, finding that there is help with the claims to there is no help to the claims generally speaking.
This study  done in 2009 did conclude that the obese subjects did show increases (shor-term) levels of insulin.  So  bottom line while no conclusive effects were found on healthy people, there could be improvement in the glucose metablism in the diabetics they studied. Blood sugar levels play a critical part in weight gain or loss.

Adverse Side Effects:  Not enough studies have been done for it's advantages or disadvantages to date, but taken in moderation, there has been no known adverse effects.  If the following sysmtoms should occur whie taking this compound supplement, one should seek medical advise:

Unexplained bruising
Skin rash or blisters
Urinate less than normal
Feel very tired
Nausea or vomiting
Sleep disturbances
Headache
Dizziness